* {
    margin: 0;
    padding: 0;
}

header {
    background-color: red;
    height: 100px;
}

article {
    background-color: green;
    height: 300px;
    overflow: hidden;
}

.middle {
    background-color: yellow;
    float: left;
    width: 100%;
    height: 300px;
}

.left {
    background-color: rebeccapurple;
    width: 100px;
    float: left;
    margin-left: -100%;
    margin-bottom: -9999px;
    padding-bottom: 9999px;
}

.right {
    background-color: palegreen;
    width: 100px;
    float: right;
    margin-left: -100%;
    margin-bottom: -9999px;
    padding-bottom: 9999px;
}

.inner {
    background-color: greenyellow;
    margin: 0 100px;
    margin-bottom: -9999px;
    padding-bottom: 9999px;
}

footer {
    background-color: grey;
    height: 100px;
    width: 100%;
    position: absolute;
}